Liquid CO2 extraction of essential oil from star anise fruits (Illicium verum H)

Essential oil from dried Star anise fruits (Illicium verum H.) was extracted with liquid CO2. The yield and the time of extraction were compared with that of the conventional steam distillation method. Extraction with liquid CO2 yielded 9.8% more essential oil than steam distillation. The anethole contents in oils obtained by the two methods were not significantly different and were in the range of 89-92% of the total oil. The particle size of 0.425-0.710 mm and the time of 90 min were found to be optimum for both steam distillation and liquid CO2 extraction. Two mathematical models were used to describe the relationship between the yield and time of extraction. Langmuir's adsorption model fitted the data better than the simple exponential model. Extraction of essential oil from Star anise fruits with liquid CO2 was better than steam distillation in terms of energy saving, product yield and product quality. (C) 1997 Elsevier Science Limited. All rights reserved.